The Left has traditionally assumed that human nature is so malleable, so perfectible, that it can be shaped in almost any direction. By contrast, a Darwinian science of human nature supports traditionalist conservatives and classical liberals in their realist view of human imperfectibility, and in their commitment to ordered liberty as rooted in natural desires, cultural traditions, and prudential judgments. Arnhart's email address is larnhart1@niu.edu.

Friday, January 28, 2011

Here I continue what I began in my previous post on Robert George's article "What is Marriage?"

About a year ago, I wrote a post on George's Kantian rationalism. According to George "reason alone" proves that abortion, embryonic stem cell research, heterosexual sodomy, and homosexual sex are immoral. "Reason alone" teaches us that marriage is self-evidently good only when it becomes a "one-flesh union" through vaginal intercourse. When a married heterosexual couple engage in any sexual activity other than vaginal intercourse, this is sodomy, and "reason alone" tells us that this is immoral.

According to George, the appeal to pure reason as a source of moral guidance does not require any appeal to the facts of human nature and history, because moral truth rests on principles that are grasped by pure logic as self-evidently true with no regard for nature or history.

Against George, I have argued that morality requires a combination of reason and desire. Natural desires provide the motivational direction for moral experience, although reason can elicit or direct desire based on judgments about the circumstances of action. Pure reason alone cannot move us to action. Both our reason and our desires reflect the facts of our human nature and history, and therefore moral experience depends on the natural history of human life.

What I find most interesting about George's new article is how it shows him pulling away from his Kantian rationalism as he recognizes that the biological facts of natural human desires shape the moral reality of human marriage. This shows him moving away from Immanuel Kant and back towards Thomas Aquinas and the Thomistic account of natural law as rooted in the natural inclinations of the human animal.

(2) AQUINAS'S MARITAL BIOLOGY
Aquinas agrees with the Roman jurist Ulpian that "natural right is that which nature has taught all animals," and this is clear in the natural inclinations to sexual mating and parental care.

This biological psychology of natural law was appropriated by Aquinas from the biological treatises of Aristotle and Albert the Great. It allows Aquinas to explain the natural law of marriage as rooted in two natural inclinations of the human animal--parental care and conjugal bonding. If human reproduction were asexual, or if human offspring could survive and flourish from birth without an extended period of care by both the mother and the father, marriage would not have arisen among human beings.

Through this biological psychology, Aquinas can explain why monogamy is universal, polygyny is common, and polyandry is extremely rare. Monogamy is natural because it satisfies both of the natural inclinations of marriage--parental care and conjugal bonding. Polygyny is partly natural, because it satisfies the natural need for procreation and parental care: one man can impregnate multiple wives and provide some care for the offspring. But polygyny is partly unnatural, because the sexual jealousy of the co-wives who tend to fight over the allocation of resources subverts conjugal bonding. Polyandry is totally unnatural, because the sexual jealousy of the husbands would be so intense that they could not live together, and because the men could never be sure of their paternity. Human biological psychology makes it easier for women to share a husband than for men to share a wife.

Notice that in contrast to George's total rejection of polygyny--or what he calls "polyamorous" marriage--Aquinas is open to recognizing the partly natural character of men with multiple wives.

Aquinas' biological psychology allows him to distinguish various levels of natural law. At the "generic" level, human beings share some natural desires with other animals. At the "specific" level, human beings share some uniquely human desires that tend to characterize most human beings. At the "temperamental" level, human beings show individual variation in those natural desires. So, for example, although sexual mating is natural for most human beings, some human individuals will be temperamentally inclined to celibacy, and thus marriage will not be natural for them.

This Thomistic biological psychology of marriage is compatible with modern evolutionary science and the neuroscience of human love. I have elaborated my reasoning for this in Darwinian Natural Right, Darwinian Conservatism, and in my article "Thomistic Natural Law as Darwinian Natural Right," which is found in Social Philosophy and Policy (winter 2001), and in Natural Law and Modern Moral Philosophy, edited by Ellen Paul, Fred Miller, and Jeffrey Paul (Cambridge University Press, 2001).

(3) EVOLUTION OF MARRIAGE
In the intellectual tradition of natural right or natural law, social order is naturally rooted in the animal instinct for parental care of offspring. Darwin showed how such social instincts could develop by natural selection in evolutionary history. "The feeling of pleasure from society," Darwin suggested, "is probably an extension of the parental or filial affections, since the social instinct seems to be developed by the young remaining for a long time with their parents; and this extension may be attributed in part to habit but chiefly to natural selection."

In the middle of the nineteenth century, Lewis Henry Morgan and other anthropologists believed that marriage and family life were not natural because originally primitive human beings were completely promiscuous in their sexual intercourse, and thus there were no enduring marital or familial ties. Karl Marx and Friedrich Engels adopted this idea as supporting the possibility of a communist abolition of the family. But Darwin rejected Morgan's claim. "I cannot believe that absolutely promiscuous intercourse prevailed in times past," he wrote, because the sexual jealousy of males and the instinctive tie between mother and child would naturally favor some kind of sexual pair-bonding and parent-child bond.

Later, Edward Westermarck's History of Human Marriage (1891) confirmed Darwin's position by surveying the anthropological evidence for concluding that marriage and the family were universal throughout history because they were rooted in some biological instincts of human nature. Because human offspring cannot survive and flourish without intensive and prolonged parental care, natural selection would favor an instinct for parental care, particularly in mothers. And although men would be more promiscuous than women, male jealousy would incline men to be possessive about their mates. The history of marriage and the family shows a complex evolutionary interaction between natural desires, customary traditions, and prudential judgments.

(4) THE NEUROSCIENCE OF THE FOUR KINDS OF MARITAL LOVE
While Darwinian evolutionary science shows the ultimate causes of marriage, the modern neuroscience of human psychology shows the proximate causes of marriage as rooted in at least four kinds of love--sexual lust, sexual romance, sexual attachment, and parental love.

Sexual lust is an indiscriminate drive for sexual arousal that seems to be connected with testosterone and other neurohormonal mechanisms. Sexual romance is a discriminate drive for sexual interest in some special person, and this seems to be connected with dopamine and perhaps serotonin. Sexual attachment is an enduring bond between husband and wife that ties them together even when the lust and romance has faded, and this seems to be connected to oxytocin and vasopressin. Finally, parental love is the attachment to children that seems to be reinforced by various neurohormonal mechanisms.

(5) GAY MARRIAGE?
If monogamous marriage based on conjugal bonding and parental care is naturally good for heterosexual men and women, would it also be good for homosexual men and women? The proponents of gay marriage think so. But George does not, because he thinks that the biological nature of marriage dictates that conjugal bonding and parental care must be heterosexual and not homosexual. I agree with George insofar as I agree that homosexuals suffer from disabilities in striving for the ideal of marriage. But I disagree with George insofar as I would stress more than he does that fullest satisfaction of homosexual desires requires some approximation to the natural ideal of heterosexual marriage.

In human sexual psychology, there is a tension between the typically male desire for sexual variety and the typically female desire for conjugal intimacy, which is a product of evolution, because in evolutionary history, the desire for variety was more adaptive for men than for women. The institution of marriage helps to tame the unruly desires of men for sexual variety by forcing them to satisfy the typically female desires for conjugal stability. Ultimately, this is good for men as well as women, because men need the intimacy and security of a stable marriage, although it's often hard for men to learn this.

The problem for homosexual males, unlike heterosexual males, is that they do not have to limit their desire for variety to accommodate the female desire for stable intimacy and the parenting of offspring, and consequently homosexual males are tempted among themselves to pursue a life of unlimited promiscuity. In contrast to lesbians, who are just like heterosexual women in their desire for stable companionship and parenting, homosexual males who try to live a life of indiscriminate sexual indulgence seem unfulfilled. Ultimately, monogamous fidelity is more satisfying even for homosexual males. Some homosexuals (such as Simon LeVay and Andrew Sullivan) argue for legalizing homosexual marriages as a way of providing social encouragement for homosexual monogamy, even as they concede that monogamous commitment is usually easier for lesbians than for male homosexuals.

George correctly observes that male homosexuals tend on average to be more promiscuous than male heterosexuals, and therefore that monogamous marriage would be more difficult for male homosexuals than for male heterosexuals. But George ignores the more monogamous propensities of lesbians, and he does not consider the likely possibility that if homosexual marriages are generally legalized, lesbians are far more likely to seek out and preserve such marriages than are gay men. Moreover, George fails to see how these lesbian marriages are likely to emulate heterosexual marriages--as is suggested, for example, in the wedding of Ellen DeGeneres and Portia de Rossi, in which Ellen dressed as the groom, and Portia dressed as the bride.

(6) PRIVATIZING MARRIAGE?
Is it true, as George assumes, that without the legal enforcement of marriage licensing law by the state, marriage would disappear? Does George agree with Andrew Sullivan--a proponent of gay marriage--who insists: "Marriage is a formal, public institution that only the government can grant"? But if marriage really is rooted in some of the deepest natural desires of human beings, as George rightly recognizes, then shouldn't we expect that marriage can stand on its own natural ground independently of the state?

In his article, George says: "marriage is not a legal construct. . . . real marriage . . . has its own value and structure, whether the state recognizes it or not, and is not changed by laws based on a false conception of it. Like the relationship between parents and their children, or between the parties to an ordinary promise, real marriages are moral realities that create moral privileges and obligations between people, independently of legal enforcement." (250). And thus, "the state cannot choose or change the essence of real marriage" (252).

But if that is the case, then why does George agree with the proponents of legalized gay marriage that the reality of marriage depends upon governmental licensing? Various people--such as David Boaz and Stephanie Coontz--have argued for "privatizing marriage." Just as we have privatized religion in modern liberal societies, we could privatize marriage, in that a marriage could be established by private contracts between individuals or between families, with or without sanction by religious authorities. Matters such as marriage and religious belief can arise in a free society through the spontaneous orders of human nature and human culture in civil society, so that government would be required only to enforce the contractual commitments that individuals have undertaken by mutual consent. Such arrangements would not be radically new, because throughout most of human history, marriages have been based on informal agreements between individuals and families without any regulation by governmental law.

In response to the advocacy for legalizing gay marriage, Thomistic Christians like George should argue that marriage is not an arbitrary construction of government, but an independent moral reality rooted in natural law and--for the religious believer--in divine law.

Monday, January 24, 2011

What difference would it make for our lives--morally, legally, and politically--if we reproduced asexually?

If you believe in a strict separation between natural facts and moral values, then you might argue that this wouldn't make any difference at all for our moral lives, because the logic of moral reasoning belongs to an autonomous realm of rational imperatives--the moral "ought"--separated from natural human needs and desires.

But to me, such a dualistic separation of human moral judgment from human bodily nature is deeply mistaken. This mistake should be clear when we reflect on how the moral experience of marriage and family life arises from our evolved human nature as sexual animals. In Darwinian Natural Right (DNR) and Darwinian Conservatism (DC), I offer a Darwinian account of marriage as shaped by our evolved natural desires for sexual identity, sexual mating, parental care, familial bonding, friendship, social status, and property (DNR, 31-32, 89-160, 261-66; DC, 28-29, 46-58).

The current debate over marriage law--and particularly, the question of whether we should legalize gay marriage--should lead us to think about the biological nature of marriage and family life. One of the most thoughtful statements to come out of this debate is the article What is Marriage? by Sherif Girgis, Robert George, and Ryan Anderson. George is one of the world's leading Catholic political philosophers, and he has offered some of the most philosophically impressive statements of the case against legalizing gay marriage. As one might expect, this latest statement has provoked responses from those defending gay marriage, such as Kenji Yoshino, a law professor at New York University. Yoshino's response to George's article has elicited a rebuttal from George, followed by another response from Yoshino, and then another rebuttal from George.

My response here to this debate will be divided into six parts. (1) I will summarize George's argument about "real marriage." (2) I will compare George's argument and Thomas Aquinas's reasoning about the biology of marriage. (3) I will comment on the Darwinian evolution of marriage. (4) I will suggest that as a result of this evolutionary history, there are potentially six different kinds of love that arise in marriage and family life. (5) I will offer a Darwinian assessment of gay marriage. (6) Finally, I will propose a Darwinian argument for resolving the debate over marriage law by privatizing marriage.

(1) GEORGE ON REAL MARRIAGEGeorge argues that any serious debate about marriage law and the possibility of legalizing gay marriage requires an answer to the question "What is Marriage?" George answers this question with a "conjugal view" of "real marriage" as opposed to a "revisionist view." He writes:

"Conjugal View: Marriage is the union of a man and a woman who make a permanent and exclusive commitment to each other of the type that is naturally (inherently) fulfilled by bearing and rearing of children together. The spouses seal (consummate) and renew their union by conjugal acts--acts that constitute the behavioral part of the process of reproduction, thus uniting them as a reproductive unit. Marriage is valuable in itself, but its inherent orientation to the bearing and rearing of children contributes to its distinctive structure, including norms of monogamy and fidelity. This link to the welfare of children also helps explain why marriage is important to the common good and why the state should recognize and regulate it.

"Revisionist View: Marriage is the union of two people (whether of the same sex or of opposite sexes) who commit to romantically loving and caring for each other and to sharing the burdens and benefits of domestic life. It is essentially a union of hearts and minds, enhanced by whatever forms of sexual intimacy both partners find agreeable. The state should recognize and regulate marriage because it has an interest in stable romantic partnerships and in the concrete needs of spouses and any children they may choose to rear." ("What is Marriage?," pp. 246-47)

In his second rebuttal to Yoshino, George summarizes his reasoning for the conjugal view of marriage in the following five paragraphs:

"Yoshino imputes to us what he labels 'the common procreation argument' about marriage, which he thinks cannot account for the validity or value of marriages that do not produce children. But we denied that actual procreation was necessary for marriage, and defended as philosophically sound the historic law of marriage that has long regarded infertility as no impediment to matrimony. For marriage is no mere means to procreation, but valuable in itself. That is perfectly consistent with holding, as we do, that the distinctive contours of marriage are what they are in significant part because it is the kind of union that would be naturally fulfilled by having and rearing children together.

"After all, any serious account must explain how marriage differs from other types of community--and make sense of the evident fact that the idea of marriage would never have been conceived if human beings did not reproduce sexually. The view that we defend and that our legal tradition long enshrined does both: Marriage, valuable in itself, is the kind of commitment inherently oriented to the bearing and rearing of children; it is naturally fulfilled by procreation. This orientation is related to the fact that marriage is uniquely embodied in the kind of act that is fulfilled by procreation: coitus. By coitus alone, a man and a woman can be related much as the organs of a single individual are related--as parts coordinating together toward a biological good of the whole. So marriage is consummated in an act that creates in this sense a bodily union--an extension of two people's union of hearts and minds along their bodily dimension, thus making marriage a uniquely comprehensive interpersonal union. (By contrast, friendships in general are unions of hearts and minds alone, and so are characteristically embodied in conversations and joint pursuits.) Finally, in view of its comprehensiveness and its orientation to children's needs, only marriage inherently requires of its would-be participants pledges of permanence, exclusivity, and monogamy. (By contrast, friendships do not require a promise of permanence and are often enhanced, not betrayed, by openness to new members.)

"Every single sentence about marriage in the previous paragraph applies equally to any man and woman who have made and consummated their marital commitment, regardless of fertility. After all, each such sentence is just as true of a couple on their wedding night as it is after the birth of a third child. By contrast, not one of these same sentences applies to two men, two women, partnerships of three or more, or by-design temporary or open unions. If Yoshino thinks that we offer no 'principled ground' for the distinctions we make, perhaps that is because his inapt label for our view ('common procreation') has clipped and obscured it.

"Nor do we salvage the validity of childless marriages at the price of denigrating their value, as Yoshino also charges. That an orientation to procreation distinguishes marriage from other unions does not mean that procreation must be the most important aspect of a marriage, much less its sole point. Comprehensive union itself--of mind, heart and body; permanent and exclusive--is of great inherent value, and distinct from the value of general friendships (unions of hearts and minds), however deep and fulfilling in their own right. Hence infertile spouses realize an important value distinguishable in significant ways from that of other relationships.

"Moreover, in agreeing that marriage is a comprehensive union of persons but denying that it includes true bodily union, Yoshino must be reducing the person to a center of consciousness and emotion, which just uses a body as an extrinsic (and thus subpersonal) instrument for achieving satisfactions or other goals. For reasons we and others have articulated in various writings, we believe that this is a serious philosophical error, one at the heart of much contemporary confusion about the meaning of sex and marriage. In truth, our bodies are integral aspects of us as human persons, so that no interpersonal union is comprehensive if it leaves out bodily union."

I generally agree with this as an eloquent and insightful statement of the biological reality of marriage as satisfying the natural human desires for sexual identity, sexual mating, conjugal love, parental care, familial bonding, and friendship. I also agree with George's suggestions, elsewhere in his writing, that marriage is a broadly social and economic institution that helps to satisfy our natural desires for social status and property.

I am also pleased to see that George recognizes that this conjugal view of marriage as rooted in human biological nature does not depend upon religious belief or appeal to any religious authority. Marriage was not invented by religion, George insists. "Instead, the demands of our common human nature have shaped (however imperfectly) all of our religious traditions to recognize this natural institution. As such, marriage is the type of social practice whose basic contours can be discerned by our common human reason, whatever our religious background" ("What is Marriage?," 247). Thus, George seems to agree with me that while religious belief can reinforce the natural biological law of marriage, that natural law can stand on its own natural ground even without religious belief (DNR, 258-66).

I am also pleased to see that George affirms the human body as an inherent part of the human person. In some of his writing, George has inclined towards a Kantian dualism that separates pure reason from the human body, which he seems to deny here.

Although George rightly cites Thomas Aquinas as stating the conjugal view of marriage, George does not see that his denigration of "polyamorous" love as contrary to real marriage contradicts what Aquinas says about polygyny (multiple wives) as "partly natural." I agree with Aquinas that although monogamy is the most natural form of marriage, polygyny can serve some of the natural ends of marriage.

Aquinas relies on Aristotle's biology to explain the biological psychology of marriage. A Darwinian evolutionary biology can explain how this psychological nature arose as a product of evolutionary history.

Moreover, modern evolutionary science and neuroscience is beginning to explain how the various kinds of human love are rooted in the neuroendocrine systems of the brain and body.

Although I generally agree with George that gay marriage can never be "real marriage," I don't think George sees how the desire of some homosexuals for something like marriage manifests their natural desire for some approximation to heterosexual marriage.

And, finally, I don't agree with George's assumption that without the legal enforcement of marriage licensing law by the state, marriage would collapse. To me, this assumption contradicts George's claim that marriage is so deeply natural for human beings that it stands on its own natural ground independently of the state. If marriage really is an expression of human natural desires, I suggest, then it should endure even if we eliminated marriage licensing laws and privatized marriage just as we have privatized religion. In a free society, matters such as marriage and religion can be shaped by human nature and human custom in civil society, with the role of government being to enforce the social commitments that individuals have undertaken by mutual consent.

Saturday, January 22, 2011

Last month, David Epstein--a professor of political science at Columbia University--was charged with having an incestuous relationship with his daughter. According to news reports, Epstein (age 46) began the affair in 2006 when his daughter was 21 years old and then stopped in 2009. If he is convicted, he could be in jail for up to four years.

This case has provoked an interesting debate among constitutional law scholars as to whether punishing Epstein for his incest would violate his constitutional rights. In 2003, the U.S. Supreme Court decision in Lawrence v. Texas struck down state criminal laws against homosexual sodomy as an unconstitutional violation of liberty. The reasoning in that decision seemed to be that consenting adults have a right to engage in any sexual behavior in private that does not harm anyone else. That reasoning would seem to extend to incestuous sexuality between consenting adults, and therefore punishing Epstein and his daughter would seem to violate their constitutional liberty. If homosexuality between consenting adults is constitutionally protected, then why isn't incest between consenting adults also protected by the Constitution?

We might think that incest is harmful because of the risk of offspring with genetic defects. But if Epstein and his daughter practiced safe sex, of if she is his step-daughter, or if he has had a vasectomy, then there would be no genetic harm.

We might also think that children can be exploited by parents in such cases. But here the daughter apparently consented to this as an adult.

William Saletan at Slate has argued that we can rightly condemn and punish incest--even between consenting adults--because it destroys the structure of family life by introducing an explosive sexual tension. This then would provide a "rational basis" for laws against incest as constitutional, and this would be consistent with the Lawrence decision, because homosexuality does not threaten family life the way incest does.

Nevertheless, Saletan doesn't believe that Epstein should be locked up.

I wouldn't prosecute David Epstein. It isn't necessary. The incest taboo is strong enough to withstand the occasional reckless fool, and I don't want cops poking around in people's sex lives. But incest is wrong. There's a rational basis to forbid it. And we shouldn't be afraid to say so.

Matthew Franck agrees with Saletan's family-structure argument for why incest is wrong. But he disagrees with Saletan on three points.

Second, he thinks that this contradicts the reasoning in the Lawrence decision, which really does make the mistake of giving constitutional protection to any sexual activity between consenting adults, which would include not only incest, but also polygamy and bestiality.

Third, he thinks that legalizing homosexual marriage could be just as destructive of marriage and family life as incest.

Franck agrees with Robert George that our marriage laws should enforce the norms of "real marriage" as a natural union of husband and wife for the procreation and care of children. Consequently, attempts to legalize homosexual marriage or incest should be rejected as contrary to the human nature of marriage and family life as the foundations for a good social order.

Thus, like George, Franck implicitly appeals to a conception of natural law as rooted in human biological nature. But he never explains--as I would--that that biological nature can be understood as a product of Darwinian evolution.

As I have argued in previous posts, the incest taboo illustrates the evolutionary nature of morality, particularly as elaborated by Edward Westermarck's Darwinian account of the incest taboo.

If the incest taboo and traditional marriage are deeply rooted in our evolved human nature, then we should expect that those natural propensities will be expressed as cultural norms that arise spontaneously in civil society. But whether those cultural norms must be legally enforced by governmental coercion is a matter of prudential judgment.

Conservatives like Franck and George think that moral norms like the incest taboo and traditional marriage will collapse if they are not enforced by the coercion of a bureaucratic state. But if these norms really are deeply rooted in human nature, why shouldn't we expect them to be expressed in the customary order of civil society even without legal enforcement?

I will elaborate these points in connection with George's arguments about "real marriage" in my next post.

Some of my posts on Westermarck and incest can be found here, here, here and here.

It's not Yasgur's Farm, but what happens at the Konrad Lorenz Institute in Altenberg, Austria this July promises to be far more transforming for the world than Woodstock. What it amounts to is a gathering of 16 biologists and philosophers of rock star stature--let's call them "the Altenberg 16"--who recognize that the theory of evolution which most practicing biologists accept and which is taught in classrooms today, is inadequate in explaining our existence. It's pre the discovery of DNA, lacks a theory for body form and does not accommodate "other" new phenomena. So the theory Charles Darwin gave us, which was dusted off and repackaged 70 years ago, seems about to be reborn as the "Extended Evolutionary Synthesis."

Proponents of intelligent-design creationism such as Paul Nelson and Casey Luskin used Mazur's reports about the "Altenberg 16" as evidence that Darwin's theory of evolution was a "theory in crisis," because it was being attacked by leading scientists. Defenders of evolution against creationism--like Nick Matzke--responded by arguing that the scientists at the Altenberg conference were not denying but deepening the foundations of evolutionary theory. This controversy over the significance of the Altenberg conference for the future of evolutionary science eventually reached the pages of the two most prominent science journals in the world, with an article by Elizabeth Pennisi in Science (July 11, 2008) and an article by John Whitfield in Nature (September 18, 2008).

Two books published in 2010 give us a clearer view of this controversy. Massimo Pigliucci and Gerd B. Muller, the organizers of the Altenberg conference, edited a book based on the papers coming out of the conference--Evolution--The Extended Synthesis (MIT Press). And Mazur published her book on the controversy--The Altenberg 16: An Expose of the Evolution Industry (North Atlantic Books, Berkeley, California).

Mazur's hysterical hatred of evolution is evident in the first paragraph of her book, where she writes that her book "looks at the rivalry in science today surrounding attempts to discover the elusive process of evolution, as rethinking evolution is pushed to the political front burner in hopes that 'survival of the fittest' ideology can be replaced with a more humane explanation for our existence and stave off further wars, economic crises and destruction of the Earth." Nevertheless, despite the vulgar journalism of her book, Mazur's interviews in the book do help to clarify the controversy.

From Mazur's book and from the more serious statement of the controversy in the book edited by Pigliucci and Muller, I draw two general conclusions. First, the "extended evolutionary synthesis" is not a denial of evolutionary theory, but is rather, as the term suggests, an extension of Darwin's theory and of the "Modern Synthesis" of evolutionary theory as stated in books like Julian Huxley's Evolution: The Modern Synthesis (first published in 1942 and now reprinted in 2010 by MIT press).

My second conclusion is that this "extended synthesis" of evolution needs to include sociobiology and evolutionary psychology. The title of Edward Wilson's 1975 book--Sociobiology: The New Synthesis--evokes Huxley's title, because, as Wilson argues in the book, he was expanding the Darwinian evolutionary synthesis to include the biological study of social behavior, which would include the cultural and moral evolution of human beings. Although most biologists have refrained from such a biological explanation of the whole of human life, Wilson realized that this was required to fulfill the expansive vision of Darwin himself, particularly in The Descent of Man. Although the evolutionary psychologists have adopted much of Wilson's project, it has been only in recent years that they have seen that an extended evolutionary account of life must include human morality and culture.

The Modern Synthesis of Huxley and others has dominated evolutionary science for almost 70 years. The synthesis is a combination of the Darwinian theory of natural selection, the Mendelian theory of genetic inheritance, and the mathematical models of population genetics. The core idea is that evolution occurs when random genetic mutations are selectively passed on to future generations because they enhance the survival and reproduction of organisms, and as a result, the changes in gene frequencies in a population eventuate in changes in phenotypic traits.

In their Introduction to their book ("Elements of an Extended Evolutionary Synthesis"), Pigliucci and Muller identify three restrictions imposed by the Modern Synthesis that are set aside by the Extended Synthesis: gradualism, externalism, and gene centrism.

The Modern Synthesis assumed that evolutionary change occurred through continuous and incremental genetic variation, so that discontinuous or abrupt changes were excluded. By contrast, in the Extended Synthesis, "various kinds of mechanisms for discontinuous change are now known from the domains of genome evolution, phenotypic plasticity, epigenetic development, and nongenetic inheritance" (13).

The externalism of the Modern Synthesis was the assumption that adaptation occurred primarily through the selective forces of external factors in the environment of organisms. By contrast, the Extended Synthesis shifts the weight of the evolutionary process from the external conditions of selection to the internal properties of organisms. "On this view, natural selection becomes a constantly operating background condition, but the specificity of its phenotypic outcome is provided by the developmental system it operates on" (13).

The Modern Synthesis is gene centric, because it assumes that all variation and inheritance is through genes. Although the Extended Synthesis does accept the importance of genes in evolution, it supports

the view of "genes as followers" in the evolutionary process, ensuring the routinization of developmental interactions, the faithfulness of their inheritance, and the progressive fixation of phenotypic traits that were initially mobilized through plastic responses of adaptive developmental systems to changing environmental conditions. In this way, evolution progresses through the capture of emergent interactions into genetic-epigenetic circuits, which are passed to and elaborated on in subsequent generations. (14)

Pigliucci and Muller sketch a conceptual framework for the Extended Synthesis as embracing three steps in "the continuous expansion of evolutionary theory."

The first step is Darwinism, which includes the ideas of variation, inheritance, and natural selection.

The second step is the Modern Synthesis, which includes the ideas of Darwinism but also the ideas of gene mutation, Mendelian inheritance, population genetics, contingency, and speciation.

The third step includes the ideas of Darwinism and the Modern Synthesis but also the new ideas of evo-devo theory (evolutionary developmental biology), plasticity and accommodation, niche construction, epigenetic inheritance, replicator theory, evolvability, multilevel selection (including group selection), and genomic evolution.

By thus presenting their Extended Theory as an expansion of evolutionary theory that includes Darwinism and the Modern Synthesis, Pigliucci and Muller make it clear that Mazur and the intelligent-design creationists were wrong to depict the Altenberg conference as overthrowing the Darwinian and Neo-Darwinian views of evolution. Even the most radical of the "Altenberg 16"--such as Stuart Newman--do not deny the fact of evolution or the importance of natural selection or the importance of genes. Rather, they embrace all of this, even as they argue that genetic mutation and natural selection are not the only factors governing evolution. So, for example, Stuart Kauffman and Stuart Newman argue that we need to see the evolutionary importance of the form-giving processes of self-assembly and self-organization as governed by the laws of physics and chemistry.

There is nothing here to support the claims of scientific creationism or intelligent design theory. Creationism and intelligent design require belief in what Darwin called "the theory of independent acts of creation"--the theory that the Creator had to intervene miraculously in natural history to specially create every form of life. Darwin wrote: "Authors of the highest eminence seem to be fully satisfied with the view that each species has been independently created. To my mind it accords better with what we know of the laws impressed on matter by the Creator, that the production and extinction of the past and present inhabitants of the world should have been due to secondary causes, like those determining the birth and death of the individual." Thus, Darwin was open to the thought that the laws of nature were originally the work of the Creator as First Cause, but that once those laws were in place, the natural history of the universe was governed by purely natural causes. When the proponents of the Extended Synthesis argue for expanding evolutionary theory to include various causal mechanisms of evolution that are not given enough weight in Darwinism or the Modern Synthesis, they are appealing not to "independent acts of creation," but to purely natural causes arising from the laws of physics, chemistry, and biology, which Darwin called the "secondary causes."

And yet, I see two defects in the way Pigliucci and Muller present their conceptual framework. The first is that they don't recognize that many of the ideas that they put outside of Darwinism were actually stated by Darwin himself. Darwin accepted the importance of what is today called epigenetic inheritance, because he accepted Lamarckian evolution. Although he believed that natural selection was the chief agent of change, he saw it as "largely aided by the inherited effects of habit, and slightly by the direct action of the surrounding conditions." Darwin also recognized the importance of multilevel selection. In fact, in David Sloan Wilson's chapter, he quotes Darwin as stating the idea of multilevel selection (82).

The second defect in the conceptual scheme of Pigliucci and Muller is that they don't include moral and cultural evolution and evolutionary psychology as part of the Extended Synthesis. Although this is not emphasized in their book, some of the authors do say that evolutionary explanations of human morality, culture, and psychology need to be part of the Extended Synthesis of evolutionary theory (68-71, 81-82, 91-92, 161-63, 175, 202, 209-10, 237-42, 469-70). After all, the emergence of human culture, human morality, and human intellect must be recognized as a major evolutionary transition that must be part of any evolutionary synthesis.

But, once again, I must point out that Darwin was there first! Darwin's Descent of Man presents an evolutionary account of human culture, morality, and psychology. It is remarkable that so many biologists have been so reluctant to accept Darwin's insight that any complete evolutionary science must include a science of human nature and culture.

This would also respond to Mazur's hysterical fear of evolution's corruption of morality by showing how evolutionary science can support the idea of a natural moral sense.

Tuesday, January 11, 2011

The best way to judge the evidence for evolution is to study the creation/evolution debate, because this allows us to see whether evolutionary science can be persuasively defended against its most relentless opponents.

High school students and college students could benefit from studying the creation/evolution debate, because this could show them how debating science ultimately raises questions in morality, politics, philosophy, and religion. Isn't this the purpose of liberal education--to see how the deepest questions of life cross all of the intellectual disciplines?

One can see this rich interdisciplinary thought in the creation/evolution debate by looking at Mark Isaak's The Counter-Creationism Handbook, which was published first by Greenwood Press in 2005 and then reprinted by the University of California Press in 2007. The book is the printed version of Isaak's online text--"An Index to Creationist Claims," which has helpful internet links.

Isaak's book is a meticulous collection of the over 400 most common claims made by creationists, along with brief answers to these claims. The creationist claims range over the full spectrum of creationism, including Biblical creationism and intelligent design theory. A point-by-point rebuttal from the Biblical creationists can be found at the "Creation Wiki", which is the online "Encyclopedia of Creation Science." Rebuttals from the proponents of intelligent design theory can be found at various sites, including the website for the Discovery Institute's "Center for Science & Culture."

Looking over Isaak's collection of creationist claims and his responses, one can see how the creation/evolution debate touches on many of the biggest questions in ethics, epistemology, psychology, mythology, religion, and history, as well as the life sciences, anthropology, geology, astronomy, cosmology, physics, and mathematics. One can almost imagine devising an entire curriculum in the liberal arts and sciences organized around this creation/evolution debate.

From my experience in debating creationists, Isaak is remarkably acute in stating their claims and in recognizing the flaws in their reasoning. Generalizing from Isaak's work, I see five fundamental flaws: (1) the implausibility of Biblical science, (2) the equivocation between human design and divine design, (3) negative argumentation, (4) the problem of ultimate explanation, and (5) the yearning for a Platonic cosmology of Mind and Purpose.

(1) The Implausibility of Biblical Science.
The Biblical creationists treat the Bible--and particularly the opening chapters of Genesis--as a science textbook. So, for example, they take the story of Noah and the flood as a literal account of a world-wide flood. Consequently, they explain geology and the fossil record as showing the effects of that flood; and they even look for Noah's Ark in Turkey. They also assume that the creation story of six days is a literal account of origins over six days that occurred about 6,000 years ago.

Isaak is meticulous and rigorous in responding to the hundreds of scientific claims that come from this literal reading of the Bible as a science textbook and in showing how scientifically implausible they are.

The fundamental mistake is the failure of the creationists to see that the Bible is a book about the relationship of human beings to God, for which the natural history of the Earth is largely irrelevant.

One can see this in the creationist assumption that the Bible shows us everything being created in 4,004 BC. In fact, this date is nowhere to be found in the text of the Bible. This date was calculated in the seventeenth century by Bishop James Ussher based on some dubious assumptions about the dating of Biblical history. Creationists have to read this into the Bible.

(2) Equivocation Between Human Design and Divine Design.
Proponents of intelligent design theory--like William Dembski and Michael Behe--try to escape the implausibility of Biblical creationism by setting aside Biblical arguments and appealing to a logic of design inference as truly scientific reasoning that does not depend on the Bible.

Dembski claims that "intelligent design is detectable; we do in fact detect it; we have reliable methods for detecting it; and its detection involves no recourse to the supernatural. Design is common, rational, and objectifiable." (Here I am drawing from my chapter on intelligent design in Darwinian Conservatism.) The problem with Dembski's logic of detecting design, however, is that it depends on equivocation in the use of the term "intelligent design."

Both Dembski and Behe speak of "intelligent design" without clearly distinguishing human "intelligent design" from divine "intelligent design." We have all observed how the human mind can cause effects that are humanly designed, and from such observable effects, we can infer the existence of human intelligent designers. We might also infer that some nonhuman animals are intelligent designers. And we might search for extraterrestrial intelligence by looking for evidence of some human-like intelligent design. But insofar as we have never directly observed a disembodied, omniscient, and omnipotent intelligence causing effects that are divinely designed, we cannot infer a divine intelligent designer from our common human experience.

(3) Negative Argumentation.
Creationists and intelligent design proponents employ a rhetoric of negative argumentation, in which they point to gaps or difficulties in evolutionary science and then assume that any such incompleteness or uncertainty in evolutionary explanation must demonstrate the truth of creationist intelligent design. Of course, this doesn't follow. Scientific knowledge will always be incomplete or uncertain, but this by itself does not prove that the proper explanation must be supernatural design. "The Intelligent Designer did it" is not an explanation. It's a confession of ignorance.

To substantiate their position, creationists and intelligent design proponents would have to explain exactly when, where, and how the intelligent designer intervened to create the irreducibly complex forms of life that we see in the world. But they generally don't do that, because that would be a burden of proof that they could not satisfy, and they benefit from enforcing standards of proof for evolutionary scientists that they themselves can never satisfy. Actually, the Biblical creationists are better than the intelligent design theorists in offering specific causal explanations--such as Noah's Flood--but then they expose themselves to refutation when the empirical evidence doesn't support such claims.

(4) The Problem of Ultimate Explanation.
In Scientific Creationism (1985), Henry Morris defends the creationist view of God as First Cause. "An omnipotent Creator is an adequate First Cause for all observable effects in the universe, whereas evolution is not an adequate cause. The universe could not be its own cause" (20). Of course, the evolutionist could ask, "But, then, who made God?" Morris answers:

"Such a question of course begs the question. If the evolutionist prefers not to believe in God, he must still believe in some kind of uncaused First Cause. He must either postulate matter coming into existence out of nothing or else matter having always existed in some primitive form. In either case, matter itself becomes its own Cause, and the creationist may well ask, "But, then, who made Matter?"

"In either case, therefore, one must simply believe--either in eternal, omnipotent Matter or else in an eternal, omnipotent, Creator God. The individual may decide which he considers more reasonable, but he should recognize this is not completely a scientific decision either way." (19)

Here's how Isaak answers this argument:

1. The assumption that every event has a cause, although common in our experience, is not necessarily universal. The apparent lack of cause for some events, such as radioactive decay, suggests that there might be exceptions. There are also hypotheses, such as alternate dimensions of time or an eternally oscillating universe, that allow a universe without a first cause.

2. By definition, a cause comes before an event. If time began with the universe, "before" does not even apply to it, and it is logically impossible that the universe be caused.

3. This claim raises the question of what caused God. If, as some claim, God does not need a cause, then by the same reasoning, neither does the universe. (262-63)

This debate over how to understand the First Cause of everything, including the laws of nature, points to the deepest problem for human understanding--the problem of ultimate explanation. All explanation depends on some ultimate reality that is unexplained. To the question of why nature has the kind of order that it has, we might answer that we must just accept this as a brute fact of our experience. That's just the way it is!

The response of the creationist is that it is very unlikely that the universe would exist uncaused, and it is more likely that God would exist as the uncaused cause of everything.

In our search for ultimate explanations, we must appeal either to nature or to God as the unexplained ground of all explanation. Thus does the natural desire to understand lead us to this most fundamental of choices--nature or God, reason or revelation. Philosophy cannot refute revelation, and theology cannot refute philosophy, because any attempted refutation would have to beg the question at issue. As Leo Strauss observed: "All alleged refutations of revelation presuppose unbelief in revelation, and all alleged refutations of philosophy presuppose already faith in revelation. There seems to be no ground common to both, and therefore superior to both."

(5) The Yearning for a Platonic Cosmology of Mind and Purpose.
One of the most common arguments from Biblical creationists and intelligent design theorists is the appeal to the "anthropic principle": the cosmos is fine-tuned to permit human life, because if any of several fundamental constants in the universe were slightly different, human life would be impossible. The claim is that this shows that the cosmos has been intelligently and benevolently designed by a cosmic Mind to sustain human life.

According to Plato's Phaedo (97c-99b), Socrates was attracted to this kind of intelligent-design cosmology in which a cosmic Mind orders all things for the best. In the Laws and the Timaeus, Plato elaborated the intelligent-design cosmology that came to dominate Western culture for almost two thousand years. A fundamental claim of this Platonic cosmology was that the supremacy of the contemplative life could be sustained by the thought that the human mind could participate in the intelligible order of the universe as designed by a cosmic Mind. Biblical religious believers could infer that this cosmic Mind was the Creator God of the Bible. The anthropic principle seems to offer modern scientific support for this Platonic/Biblical cosmology.

But rather than refuting evolution, the anthropic principle can be understood in a way that supports evolutionary reasoning. As Isaak suggests, evolutionary thinking proposes not that the cosmos is fine-turned to life, but that life is fine-tuned to the cosmos, because life has evolved in adaptation to the cosmos, which includes the adaptation of the human mind for understanding the cosmos. Of course, this evolutionary adaptation is imperfect, and therefore we have no reason to think that this is the best of all possible worlds. The human mind is fallible in ways that we can explain as a product of evolutionary history. But even with its fallibility, the human mind is capable of endless exploration in striving to satisfy the natural human desire for understanding.

So even if the natural world was not made for us, we were made for it, because we are adapted to live in it. We come from nature. It is our home.

Or, as Strauss once wrote: "Becoming aware of the dignity of the mind, we realize the true ground of the dignity of man and therewith of the goodness of the world, whether we understand it as created or uncreated, which is the home of man because it is the home of the human mind."

Monday, January 10, 2011

In my previous post, I linked to Peter Lawler's post on Darwinian conservatism. There is now a comment on Lawler's post from Brendan Foht, which raises some good questions.

Foht suggests that I am promoting a Darwinian historicism that denies the eternity of human nature as an unchanging essence. He writes:

What bugs me about Arnhart's "Darwinian" philosophy is that it doesn't seem to come to grips with what is really unique in the Darwinian mode of explanation. He talks about this grab-bag list of twenty "natural" desires, and how we ought to use an empirically based understanding of nature as the standard for politics. That's all well and good, but why do you need Darwin to find these twenty natural desires? Ordinary social science (or for that matter, common sense) could tell you that human beings like to have families or practical arts or what-have-you. What makes Darwinian explanation special compared to old-fashioned empirical naturalism is that it stands nature on its head. According to an old-fashioned understanding of nature, nature is the force that makes us who we are, i.e. our essence. For Darwin, however, nature is itself made by an historical process of competition and selection. Our nature is no longer an essence; it is just another historical accident. So I'm not sure how much Darwinism really helps us argue against techno-liberationist policies like transhumanism. If we happen to dislike some aspect of our nature, and we happen to have the technical means to change it, why should it be evolutionary biology that gives us pause?

The real problem for a post-Darwinian political philosophy (conservative or otherwise) is not how to replace "metaphysical" values with "natural" values, but how to reconcile the project of "natural" morality with the historicism of Darwin's nature.

On the first point, I agree that recognizing the twenty natural desires is a matter of common-sense experience that does not require Darwinian science. The value of Darwinian science here is in providing scientific confirmation for this common-sense knowledge by showing the ultimate natural causes for these natural desires in the evolutionary history of the human species.

But that appeal to the evolutionary history of the human species leads to Foht's second point--his worry about Darwinian historicism.

Foht invokes "an old-fashioned understanding of nature" in which "nature is the force that makes us who we are, i.e. our essence," and he contrasts this to "the historicism of Darwin's nature." I assume that Foht is referring here to some kind of Platonic metaphysics of the Theory of Ideas in which human nature is an eternally unchanging Idea or Essence. Alternatively, Foht could be a Christian Platonist who sees God as the Creator of human nature as an everlasting essence.

As I have indicated in many previous posts, I regard Platonic metaphysics as implausible. In fact, it is so implausible that it is not even clear that Plato or Plato's Socrates ever clearly endorses it. (Here I am using some language from some previous posts.)

If Darwin's evolutionary science is correct, then all the species of life come into being and pass away. Species are not eternal or everlasting, but they are real for as long as they last. When Louis Agassiz wrote a critical assessment of Darwin's theory, Darwin wrote to Asa Gray, in a letter of August 11, 1860, that he was "surprised that Agassiz did not succeed in writing something better. How absurd that logical quibble: 'if species do not exist, how can they vary?' As if anyone doubted their temporary existence."

To affirm the "temporary existence" of species denies the Platonic/Socratic teaching that Being--what is really real and fully intelligible--must be eternal and unchanging, as distinguished from the temporal and ever-changing flux of the sensible world.

But as long as we adhere to this Parmenidean assumption that Being is eternally unchanging, we cannot bridge the gap between the unchanging ideas and changing sense experience. This absolute separation of unchanging intelligibles and changing sensibles cannot explain human knowledge, because human cognition is in motion. The intelligibility of being seems to require that it somehow be both in motion and at rest. But, still, we can understand the world by sorting things into classes according to the ways they are like or unlike one another.

We need to go beyond the Parmenidean and Platonic search for invariants and see that reality is a mixture of fixity and flux. We need to see that the history of the cosmos shows an evolutionary emergence of variance and novelty. We can sort things out according to their enduring patterns of similarity and difference. But these enduring patterns are not eternal or everlasting.

This is certainly true for our study of human nature. The human species is not absolutely invariant or eternal. Human beings did not exist before the evolutionary emergence of Homo sapiens, and we can expect that some day the human species will go extinct. But for as long as our species exists, there will be natural propensities and traits that characterize us--including the twenty natural desires.

And yet the present reality of the human species is not invariant, because each human being is unique in being a product of a unique natural history. Biological history depends upon the variation that comes from genetic mutation and from sexual mating, in which the random assortment of genes results in the production of unique individuals. So while we can identify the human species as a range of traits or propensities, we know that within that range, there is immense variation expressed in individual diversity. Human nature as we know it is neither absolutely fixed nor absolutely chaotic.

Without realizing it, Catherine Zuckert--in her Straussian interpretation of Plato--implicitly endorses this Darwinian understanding of the human species in her criticisms of Timaeus's cosmological explanation of the human species. As she indicates, Timaeus cannot account for the unpredictable variation in human beings that comes from human mating and reproduction, because he has to assume that the divine craftsman created human nature as absolutely unchanging. Consequently, Timaeus has to assume that all human beings are born absolutely the same in their natural abilities and traits, which denies the reality of natural individual differences. Thus, as Zuckert indicates, Timaeus's cosmology--in its search for eternal invariance--must deny the obvious facts of sexual reproduction and individual identity.

Some Straussian scholars try to avoid these problems associated with the Platonic Theory of the Ideas. They do that by claiming that this teaching is only a "noble lie" for Plato to satisfy the popular need for a cosmologically supported morality. But the Straussians also want to say that the Platonic teaching about the supremacy of the philosophic life is simply true, and they never explain how this can be sustained without a Platonic cosmology in which Mind rules over all, and philosophy somehow participates in the cosmological intelligibility of the eternal Mind.

My conclusion from all this is that Platonic conceptions of cosmic teleology and the eternity of species are implausible, because they contradict what we know by experience. More plausible, I suggest, is the Darwinian conceptions of immanent teleology and the evolution of species.

But what, then, should we say about Foht's third point--his worry about a transhumanist use of biotechnology to change human nature? First of all, I don't understand why this is a worry for him if he really believes that human nature is eternal and unchanging. If he really believes this, then he should believe that a tranhumanist transformation in human nature is impossible.

As I have indicated in some previous posts, my Darwinian response to transhumanist biotechnology is to argue that the technology for enhancing human powers will be limited both in its technical means and in its moral ends. It will be limited in its technical means, because complex behavioral traits arise from the intricate interplay of many genes interacting with developmental contingencies and unique life histories to form brains that constantly change as they respond flexibly to changing circumstances. Consequently, precise technological manipulation of human nature to enhance desirable traits while avoiding undesirable side effects will be difficult if not impossible.

The technology of human enhancement will also be limited in its moral ends. Human beings act to satisfy their natural desires. The use of technology to enhance human life will be driven by these natural desires. Transhumanists implicitly assume the enduring power of these desires--for example, the natural desire of parents to promote the happiness of their children. But if that is the case, then it is hard to see how human nature is going to be abolished if the natural desires endure.

Saturday, January 08, 2011

Over at the "Big Think" website, Peter Augustine Lawler has written a blog post on Darwinian conservatism.

This essay is a good short statement of Peter's points of agreement and disagreement with me. He agrees that Darwinian conservatism offers a sensible understanding of human beings as social and political animals. His disagreement comes from his belief that this cannot be the whole truth about human beings, because it cannot explain the transcendent longings of the human soul, which can only be explained through a metaphysical conservatism.

Thursday, January 06, 2011

Friedrich Hayek once said: "The curious task of economics is to illustrate to men how little they really know about what they imagine they can design."

This quotation concludes an excellent blog post at "Cafe Hayek" by Russ Roberts. He argues that economics is not a science in the same way that mathematical physics is a science, because economics is more like Darwinian biology in that it tries to understand social systems that are too complex and contingent to be reduced to mathematical models that have any precisely predictive power. The failure of macroeconomists to predict the Great Recession or to predict exactly the consequences of present economic policies designed to bring recovery illustrates this point.

This is a good statement that reinforces what I have said about the "lawlessness" of the social sciences, which is shared by the life sciences. This also reinforces my arguments for defending the ancient understanding of prudence and practical judgment against the delusions of the modern dream of a fully mathematicized science.

Thinking through some of these questions will be the concern of my forthcoming Liberty Fund conference on "Hayek and the Problem of Scientific Knowledge."

Tuesday, January 04, 2011

In 1966, I was in my junior year at Big Spring High School in Big Spring, Texas. Knowing that I would be taking a course in biology, I prepared for the class by studying all the arguments against the theory of evolution and in favor of Biblical creationism. As I sat in the class, I waited for the day when the teacher would bring up the topic of evolution so that I could show off how smart I was by exposing the false claims of evolutionary theory. When we reached the last few weeks of the class, I became agitated because the teacher had said nothing about evolution. Finally, I questioned him in class about when we would be discussing evolution, he responded with some evasive remarks about how there might not be enough time to discuss evolution. I talked with him after class, and I discovered that like many high school biology teachers in Texas, he was afraid to bring up the topic of evolution because it was too controversial with parents.

A few years later, I changed my mind when I decided that the evidence for evolution was plausible enough to be convincing. But I still believed--and believe today--that high school students and college students should be allowed in their biology classes to weigh the evidence for and against evolution by reading some of Darwin's writings, some of the contemporary writing of evolutionary theorists, and some of the critical writing coming from proponents of creationism and intelligent design theory as alternatives to evolution. So here I agree with those proponents of intelligent design theory (particularly, those at the Discovery Institute) who argue for "teaching the controversy" in high school biology classes. But I believe that if students are permitted to make up their own minds after a fair presentation of the debate, most of them will see that the weight of the evidence and the arguments favors evolutionary theory.

One good book for this purpose would be Richard Dawkins' The Greatest Show on Earth: The Evidence for Evolution (Free Press, 2009). Dawkins surveys ten lines of evidence for evolution that should be considered in any debate over evolutionary theory. But while Dawkins himself doesn't believe in "teaching the controversy," his book shows that one cannot properly judge the truth of evolution without comparing it with the alternatives. One should also see the defects in Dawkins' presentation of evolution, insofar as he ignores or plays down some of the most important lines of evolutionary thought.

TEN KINDS OF EVIDENCEDawkins rightly indicates that the theory of evolution--like any scientific theory--cannot be proven in a demonstrative way, as we prove a mathematical theorem as a conclusion that follows necessarily from axiomatic principles. The best we can hope for is to prove it "beyond a reasonable doubt." The biggest problem is that most evolutionary change has occurred in the distant past, and therefore it's not open to direct eye-witness observation. We are like detectives who to the scene of a crime after it has been committed, and we must look for evidence that will allow us to infer what happened. There are at least ten kinds of such evidence for evolution.

(1) Artificial selection and natural selection.Like Darwin in The Origin of Species, Dawkins begins with the evidence from the human domestication of plants and animals. The history of human beings breeding plants and animals for human purposes shows evolutionary change from artificial selection. This is not just an analogy for natural selection but an experimental test of Darwin's claim that heritable variation open to selective pressures will produce evolutionary change(66).

Dawkins does not acknowledge one problem with the argument from human breeding: although the human domestication of plants and animals shows something like microevolution, it's not clear that this shows macroevolution. The various breeds of dogs are very different from one another, but they are all members of the same species.

Of course, natural selection does not show the intentional design present in human breeding, but natural selection can work through animals acting as selective breeders. For example, insects have created brightly colored flowers by selective breeding through their behavior in cross-pollinating plants; and some females have exercised sexual selection in selectively breeding with those males that are most attractive to them.

(2) Evolutionary clocks.Evolutionary history must extend over millions or even billions of years, and therefore it's crucial to have techniques for measuring such long time scales. Dawkins explains how various kinds of evolutionary clocks--tree-ring clocks, radioactive clocks, and molecular clocks--provide the necessary measurement for evolutionary time. If one agrees with the Biblical creationists that everything was created about 6,000 years ago, then one would have to refute the accuracy of these evolutionary clocks.

(3) Natural selection in the wild and in the lab.Richard Lenski has shown how bacteria (E. coli) can evolve in the laboratory. John Endler has shown how wild guppies in Trinidad can evolve in different environmental conditions. For Dawkins, these are examples of evolution in action--evolution that we can actually observe directly.

Again, however, we have the problem that this seems to show microevolution (evolutionary change within a species) but not macroevolution (evolutionary change from one species to another). The assumption that the small changes of microevolution can eventually add up to the large changes of macroevolution needs to be proven.

(4) The fossil record.Because of the conditions required for the creation of fossils, we cannot reasonably expect a complete fossil record of evolutionary history. But so far, nothing in the fossil record as we know it refutes evolutionary theory.

Contrary to the common claim that Darwinian evolution is unfalsifiable, Darwin's theory could by falsified by finding fossils indicating the appearance of life forms earlier than would be possible by evolution. For example, if we found fossils of mammalian life in the Cambrian period (500 million years ago) or earlier, that would refute the theory. So far, no such fossils have ever been found.

Despite the common talk about "missing links," there are lots of fossils showing intermediate links in evolutionary history. For example, Neil Shubin's discovery of Tiktaalik looks like the perfect link between fish and amphibians.

(5) The human fossil record.When Darwin wrote The Origin of Species in 1859, there were no ancestral human fossils. But in The Descent of Man, Darwin predicted that earliest human fossils would be found in Africa. This prediction has been confirmed. The human fossil record has grown so that now we have an impressive record of human ancestry from Australopithecus africanus to Homo habilis to Homo erectus to Homo sapiens that allows us to trace the evolution of crucial human traits such as bipedal gait and large cranial capacity.

(6) Evolutionary embryology. To fully understand evolution, we would have to understand how evolutionary changes have worked through changes in embryological development. Although our knowledge of this is still severely limited, we are beginning to understand how living beings grow through self-assembly. Dawkins stresses that "it's all done by individual cells obeying local rules" as opposed to top-down design through global rules.

How the natural selection of genes controls embryology is still mysterious in practice, Dawkins says, but not in principle. Here is where Dawkins should have said more about the ideas coming out of evolutionary developmental biology (see below).

(7) Geographical distribution.A likely crucial factor for macroevolution is that two populations within a species become isolated from one another long enough so that when reunited, they cannot interbreed and thus become separate species. The clearest example of this is geographical isolation.

Darwin's studies of the flora and fauna of the Galapagos islands are rightly famous in suggesting how species become adapted to different geographic areas. The diversity of species across the islands and the similarities to species on the South American mainland suggest that species from the mainland migrated to the islands and then radiated out across the islands. That we see many species that are unique to the Galapagos and yet similar to those on the mainland suggest evolutionary adaptation.

It's hard to understand how creationism or intelligent design theory could offer more plausible explanations. If all species originally came from Noah's Ark on Mt. Ararat, why did certain species go to the Galapagos islands and not go anywhere else? The same question could be raised about species unique to Madagascar or Australia.

The well-grounded theory of continental drift or plate tectonics explains how species could have been isolated geographically and then adapted to their locations.

(8) Patterns of resemblance in the tree of life.The living world shows patterns of resemblance that show a family tree of evolutionary descent. So, for example, the skeletons of all mammals show the same fundamental pattern, although their individual bones are different. On the other hand, no mammals have feathers.

As an alternative explanation, we might say that the patterns of resemblance show recurrent themes in the mind of the Creator or Intelligent Designer. But if the Designer regards feathers as such a good idea, why don't mammals have them?

Advancing knowledge in genetic science now allow us to trace the genetic evidence for common ancestry. If chimpanzees and bonobos are our closest living relatives, as evolutionary science claims, then there should be a very close genetic similarity, and indeed there is.

(9) Historical vestiges of evolution.If evolutionary theory is correct, we should see "design flaws" that reflect the vagaries of evolutionary history, which we would not expect to see if we thought it was all the work of an intelligent designer. In fact, we see some birds with wings that cannot fly and salamanders with eyes that cannot see. Vestigial wings and vestigial eyes are evidence of evolutionary history in which animal species have undergone awkward adjustments to evolutionary change.

(10) Evolutionary arms races.If evolutionary theory is correct, we should expect to see organisms competing for scarce resources in ways that do not always promote the collective welfare of the whole ecosystem. And, indeed, we see such costly competition--for example, predators and prey competing in runaway "arms races" where every defensive maneuver of the prey species is followed by an offensive maneuver of the predator species. The costliness of such arrangements and the massive suffering produced by this war of nature is hard to explain as the product of a beneficent designer.

Weighing the persuasiveness of these ten lines of evidence for the theory of evolution depends on the comparative persuasiveness of alternative theories. That's why I think we need to see the fundamental controversy.

TEACHING THE CONTROVERSYAs far as I can tell, most of the leading proponents of evolutionary science today--including Dawkins--reject the idea of "teaching the controversy" by allowing students to weight the evidence for evolution against the evidence for creation or intelligent design. After all, they insist, there really is no controversy, because evolutionary science is generally accepted by scientists, and the scientific disputes over evolution are not really about the general theory.

By contrast, I have argued--here and here--that we cannot teach the science of evolution if we don't teach the controversy. If we teach students to simply memorize the concepts of evolution without critically questioning the evidence and arguments supporting those concepts, then we conveying the thought that science is a matter of dogmatic belief rather than reasoned debate.

We can see this in the writing both of Darwin and of Dawkins. Throughout the Origin of Species and The Descent of Man, Darwin compares his "theory of natural selection" with the "theory of special creation" in arguing that his theory is more plausible by comparison. Although Dawkins refuses to specifically cite the authors and texts of creationist and intelligent design theory, he repeatedly in his book shows how the evidence for evolution is most persuasive when compared with what would be predicted by creationism or intelligent design theory.

If students were allowed to actually read some of the writing for creationism and intelligent design, they could critically judge Dawkins' claims. For example, they might notice that Michael Behe--a biologist supporting intelligent design--actually accepts the genetic evidence for common evolutionary ancestry, including the primate ancestry of human beings. Moreover, they might also notice that according to Behe, we cannot know whether the intelligent designer is "a dope, a demon, or a deity." Students might also see that Behe ridicules the idea of taking the Bible as a science textbook. The students might conclude that Dawkins is employing a crude rhetoric of distortion that does not confront the true complexity of the intelligent design position. (Some of my posts on Behe can be found here and here.)

If the students were allowed to do some reading in evolutionary theory beyond Dawkins that might notice that he ignores or plays down many of the lines of research that are becoming prominent today among evolutionary theorists.

EVOLUTION BEYOND DAWKINS(1) Moral evolution.As I indicated in my previous post yesterday, Dawkins has generally insisted throughout his career that morality cannot be explained by evolutionary science, and therefore that the most important features of human life are beyond natural science. But in making this argument, he rejects Darwin's ethical theory in The Descent of Man.

Most recently, however, Dawkins' endorsement of Sam Harris's The Moral Landscape suggests that Dawkins has changed his mind and that he is now following the lead of other evolutionary theorists who are working on evolutionary explanations of human morality.

(2) Epigenetic evolution.Like other Neo-Darwinians in the tradition of the "Modern Synthesis" of evolutionary biology, Dawkins assumes that genes are the only units of selection and that there is no Lamarckian inheritance of acquired characters. In recent years, this Modern Synthesis has been thrown into doubt. In particular, there is growing recognition of epigenetic mechanisms that allow for Lamarckian evolution. This has been the subject of a previous post. Dawkins is scornful of the idea of epigenetic evolution, which he dismisses in a footnote (216). Actually, the recent recognition of epigenetic evolution is a return to Darwin, who saw the importance of Lamarckian evolution.

(3) Gene-culture coevolution.Some of the most important research in evolutionary theory--particularly as applied to human beings--is in understanding the evolutionary interaction of genes and culture. This is also a return to Darwin. Although he did not understand genetics, he did understand the importance of culture evolution as interacting with innate predispositions. Some of my posts on this can be found here and here.

Although Dawkins originated the idea of "memes" as units of cultural evolution, he mentions this only briefly in this latest book (406-408).

(4) Group selection.As the proponent of the "selfish genes" theory of evolution, Dawkins is a vehement opponent of group selection--the idea that evolutionary selection can occur at the level of groups. Dawkins denies that Darwin endorsed group selection, but this is clearly wrong (62, 390, 393). In The Descent of Man, Darwin emphasized the importance of group-against-group competition in evolutionary history. Recent work by David Sloan Wilson and E. O. Wilson has confirmed that Darwin was right about this.

(5) Evo Devo.In recent decades, some evolutionary theorists have become ever more skeptical that the Neo-Darwinian Modern Synthesis can explain how the mechanisms of microevolution lead to the macroevolution of new species. As an alternative, there is growing interest in evolutionary developmental biology--"Evo Devo"--as perhaps providing a new set of explanations. We need to understand how regulatory genes during embryonic development turn the other genes on and off at different times and places in the body, and how evolutionary change in these "genetic switches" might account for macroevolution. This has been the subject of a previous post.

Dawkins implicitly recognizes the importance of this research when he talks about "the evolution of evolvability" as a property of embryologies (423-24). But, remarkably, he does not explicitly speak of this as Evo Devo or cite any of the leading exponents, such as Sean Carroll.

(6) Religion.As a vehement atheist, Dawkins has no interest in considering how evolutionary theory and religious belief might be compatible. He does at least acknowledge that some Christians--including some Anglican and Catholic bishops--have collaborated with him in writing some public statements endorsing evolution, and he thus recognizes the possibility of theistic evolution in which God uses the evolutionary process to execute his will. But it's impossible for Dawkins to take this seriously (5-6). Similarly, he cannot take seriously Darwin's conception of the Creator as the source of the natural laws underlying evolution and as the original source of matter, energy, and life (403-404). Dawkins refuses to admit that even if Darwin was not an orthodox Christian, Darwin was open to the possibility of God as the ultimate ground of natural order.

Moreover, Dawkins has nothing to say about the recent research on the evolutionary origins of religious belief, which supports my claim that there is an evolved natural desire for religious understanding. Links to some of my previous posts on this can be found here.

If students were allowed to actually read Darwin in their biology courses, they might notice that most of this new research in evolutionary science is reviving ideas that were already there in Darwin's writings, which confirms the thought that although there has been much progress in evolutionary science since Darwin wrote, no one has surpassed his genius in anticipating most of the major insights in evolutionary reasoning.

Monday, January 03, 2011

Sam Harris has become famous in recent years as one of the "new atheists." Like Richard Dawkins, he argues that if we look to science as a source of truth about the world, then we must reject religion as a source of falsehood.

Now Harris has provoked an intense controversy among his fellow scientific atheists, because he rejects the common assumption that science cannot teach moral truth and argues, on the contrary, that biological science can help us to understand objective moral truth. The controversy began last year when he appeared at a TED Conference and gave a talk entitled "Science Can Answer Moral Questions." This talk briefly summarized the reasoning that he has elaborated in a recent book--The Moral Landscape: How Science Can Determine Human Values (Free Press, 2010).

Remarkably, Harris's book has forced Richard Dawkins to change his mind. Having argued throughout his life that science--and particularly Darwinian science--cannot tell us about moral truth, Dawkins now says that Harris is right about the scientific grounds of morality. Oddly enough, this means that Dawkins, who is famous as an "ultra-Darwinist," has now finally given up his disagreement with Charles Darwin's claim that human morality is rooted in evolved human nature!

At the beginning of The Moral Landscape (1-2), Harris says that he will argue

that questions of value--about meaning, morality, and life's larger purpose--are really questions about the well-being of conscious creatures. Values, therefore, translate into facts that can be scientifically understood: regarding positive and negative social emotions, retributive impulses, the effects of specific laws and social institutions on human relationships, the neurophysiology of happiness and suffering, etc. The most important of these facts are bound to transcend culture--just as facts about physical and mental health do. Cancer in the highlands of New Guinea is still cancer; cholera is still cholera; schizophrenia is still schizophrenia; and so, too, I will argue, compassion is still compassion, and well-being is still well-being. And if there are important cultural differences in how people flourish--if, for instance, there are incompatible but equivalent ways to raise happy, intelligent, and creative children--these differences are also facts that must depend upon the organization of the human brain. In principle, therefore, we can account for the ways in which culture defines us within the context of neuroscience and psychology. The more we understand ourselves at the level of the brain, the more we will see that there are right and wrong answers to questions of human values.

In a previous post, I have shown how Dawkins and most of the proponents of evolutionary psychology have rejected E. O. Wilson's sociobiological ethics, and in doing that, they have rejected Darwin's evolutionary account of ethics in his Descent of Man. Most of the leaders of evolutionary psychology have agreed with Dawkins' Kantian dualism, as expressed in the last paragraph of Dawkins' book The Selfish Gene. Dawkins proclaimed that human beings were unique in their capacity for "deliberately cultivating and nurturing pure, disinterested altruism--something that has no place in nature, something that has never existed before in the whole history of the world." "We alone on earth," Dawkins concluded, "can rebel against the tyranny of the selfish replicators."

In a 1997 interview, Dawkins explained: "What I am now saying, along with many other people, among them T. H. Huxley, is that in our political and social life we are entitled to throw out Darwinism, to say we don't want to live in a Darwinian world. We may want to live in, say, a socialist world that is very un-Darwinian."

Although most of the proponents of evolutionary psychology have agreed with Dawkins in this claim that there is no basis in Darwinian science for morality, many of them have changed their minds in recent years, because the Darwinian explanation for morality has become a vibrant area of research for evolutionary psychologists. Some of my previous posts on this can be found here and here.

Now, apparently, Dawkins has experienced a similar change of mind. The back of Harris's book has the following blurb from Dawkins: "I was one of those who had unthinkingly bought into the hectoring myth that science can say nothing about morals. The Moral Landscape has changed all that for me. Moral philosophers, too, will find their world exhilaratingly turned upside down, as they discover a need to learn some neuroscience. As for religion, and the preposterous idea that we need God to be good, nobody wields a sharper bayonet than Sam Harris."

The abruptness of this change of mind is evident if one looks at Dawkins' most recent book The Greatest Show on Earth: The Evidence for Evolution (published in 2009). In this book (pp. 390-96, 400-402), Dawkins agrees with Stephen Jay Gould's essay on "Nonmoral Nature," in which Gould argues that there is no ground in evolutionary nature for morality. Gould concludes: "If nature is nonmoral, then evolution cannot teach any ethical theory." Gould asserts that this was Darwin's position. But in doing that, Gould has to completely ignore Darwin's ethical theory in the Descent of Man, in which Darwin explains the "moral sense" as a product of human evolution. If evolved human nature is moral, Darwin suggests, then evolution can teach an ethical theory rooted in human nature.

But notice the critical point here that is commonly overlooked by modern scientists and philosophers: Darwin's evolutionary theory of ethics is grounded not in cosmic nature but in human nature. In this way, Darwin's theory of ethics is in the empirical tradition of Aristotle and Hume rather than the metaphysical tradition of Plato and Kant.

Darwin's Kantian critics--like Frances Cobbe--saw this, and they were appalled that Darwin was grounding ethics in the evolved order of human nature rather than the eternal order of cosmic imperatives. Since most modern moral philosophers are still implicitly in the grip of Kantian or Platonic conceptions of moral cosmology, they believe that if morality is not written into the fabric of the cosmos, then morality is purely "fictional."

By contrast, as I have argued, a Darwinian science of morality would be based not on a Cosmic God, Cosmic Nature, or Cosmic Reason, but on human nature, human tradition, and human judgment. Some of my posts on this can be found herehere, and here.

Moral truth is not a cosmic truth but a human truth, a truth about what is required for the happiness or flourishing of human beings as products of natural evolution. This insight runs through the moral biology of Aristotle, Hume, and Darwin.

Regrettably, Harris does not have a clear grasp of this point. Occasionally, he recognizes that his argument is in the tradition of Aristotle and the Aristotelian understanding of ethics as directed to human happiness or flourishing (195-96). And, occasionally, he sees that his Darwinian empiricism is opposed to Platonic cosmology. He writes:

"I am certainly not claiming that moral truths exist independent of the experience of conscious beings--like the Platonic Form of the Good--or that certain actions are intrinsically wrong. I am simply saying that, given that there are facts--real facts--to be known about how conscious creatures can experience the worst possible misery and the greatest possible well-being, it is objectively true to say that there are right and wrong answers to moral questions, whether or not we can always answer these questions in practice." (30)

"We do not require a metaphysical repository of right and wrong, or actions that are mysteriously right or wrong in themselves, for there to be right and wrong answers to moral questions: we simply need a landscape of possible experiences that can be traversed in some orderly way in light of how the universe actually is. The main criterion, therefore, is that misery and well-being not be completely random. It seems to me that we already know that they are not--and, therefore, that it is possible for a person to be right or wrong about how to move from one state to another." (198)

But, then, elsewhere in his book, Harris invokes a Kantian rationalism of moral imperatives as if ethics were impossible without a "moral ought" that belongs to some a priori realm of moral truths that exist independently of natural human experience (81-83, 101, 199, 204-205, 210).

It would be better for Harris's argument if he were to clearly defend the empiricist tradition of Darwinian ethics against the transcendentalist tradition of Kantian ethics. If he were to do that, he could argue that, contrary to Kant, moral judgments are based not on categorical imperatives but on hypothetical imperatives. I have elaborated this point in some other posts..